Microdamage Of Material Research Articles

Characterization of Contact‐Type Defects in Mortar Using a Nonlinear Ultrasonic Method

Second harmonic generation (SHG) is one of the common techniques in the nonlinear ultrasonic test. The contact‐type defects play an important role in material damage, which are hard to be detected. The traditional nonlinear parameter β used to evaluate the micro damage in material is derived from the classical stress‐strain relation, which is more suitable for the anharmonicity of crystal rather than the contact‐type defects. Recently, the theoretical model based on the bilinear stiffness law was derived, and the validity and applicability need to be further studied. For this purpose, by the numerical method, the contact interface in mortar is characterized based on the damage indicator γ. The relation between the excitation voltage and γ is obtained. Moreover, the effects of the crack length and orientation on the damage indicator γ are also obtained. The experimental method is also used to characterize the contact interface in mortar. Combining with the existing work, the results obtained in this article are discussed, and further conclusions can be drawn. The conclusions in this article provide potential of quantitative detection of the contact interface and quality evaluation of bonding layers in materials.

Scanning non-collinear wave mixing for nonlinear ultrasonic detection and localization of plasticity

Non-collinear wave mixing recently has been proposed to detect and localize micro-damage in materials. It is proved sensitive to the interaction angle α of the incident waves. In this work, the relationship between the acoustic nonlinearity parameter χ and the α is studied by numerical simulations and experimental measurements based on the nonlinear interaction of two shear waves. A single-peak change in the normalized acoustic nonlinearity parameter χ′ of the mixing wave versus the incident angle is observed from numerical simulations and then is verified by experiments. The results show a -6 dB decrease of χ′ corresponds to a deviation of about 4° in the incident angle. Meanwhile, the detection and localization of plastic deformation is also conducted on an aluminum alloy based on the scanning of non-collinear wave mixing, in which the distribution of the acoustic nonlinearity is similar to that of the plastic strain.

Erratum to: Nonlinear ultrasonic techniques for nondestructive assessment of micro damage in material: A review

Erratum to: Nonlinear ultrasonic techniques for nondestructive assessment of micro damage in material: A review

Nonlinear ultrasonic techniques for nondestructive assessment of micro damage in material: A review

The nondestructive assessment of the damage that occurs in components during service plays a key role for condition monitoring and residual life estimation of in-service components/structures. Ultrasound has been widely utilized for this; however most of these conventional methods using ultrasonic characteristics in the linear elastic region are only sensitive to gross defects but much less sensitive to micro-damage. Recently, the nonlinear ultrasonic technique, which uses nonlinear ultrasonic behavior such as higher-harmonic generation, subharmonic generation, nonlinear resonance, or mixed frequency response, has been studied as a positive method for overcoming this limitation. In this paper, overall progress in this technique is reviewed with the brief introduction of basic principle in the application of each nonlinear ultrasonic phenomenon.

An Integrated Simulation Environment Realizing the Ability of Nano-Photonic Crystals to Detect and Quantify Submicron and Microdamage in Materials

An Integrated Simulation Environment Realizing the Ability of Nano-Photonic Crystals to Detect and Quantify Submicron and Microdamage in Materials

Prediction of resources of materials of machine and construction elements in the process of manufacture and exploitation

A combined phenomenological concept of the fracture prediction of machine and construction elements, including both the technology of their manufacture and their exploitation, is suggested in this work. The concept is based on introducing a computed scalar character of micro-damage of material. A kinetic equation describes both the process of damage accumulation and the “curing” of this damages. Calculation of the micro-damage character is carried out by consideration of the boundary problem of stress-strain and the heat state of the metals.

Initial Development of Microdamage Under Impact Loading

In this paper, the initial development of microdamage in material subjected to impulsive loading was investigated experimentally and analytically with controllable short-load duration. Based on a general solution to the statistical evolution of a one-dimensional system of ideal microcracks, a prerequisite to experimental investigation of nucleation of microcracks was derived. By counting the number of microcracks, the distribution of nucleation of microcracks was studied. The law of the nucleation rate of microcracks can be expressed as a separable function of stress and cracksize. It is roughly linear dependence on loading stress. The normalized number density of microcracks is in agreement with that of a second-phase particle.

On The Nature Of The Accumulation Effect In Laser-Induced Damage To Optical Materials

Features of multiple-shot laser-induced damage to optical materials are analyzed. The methodology of studying the accumulation effect responsible for catastrophic damage, based on the statistical approach, is suggested, and the basic characteristics of multiple-shot damage are introduced. Possible mechanisms of microdamage in materials under multiple laser irradiation are discussed. The experimental data on the laser-induced damage to optical polymer materials which demonstrate some basic properties of the accumulation effect are presented. The ways of suppressing the accumulation effect in transparent polymers which result in a considerable increase of laser damage resistance are proposed.